This invention relates to a knitting machine and a control jack for controlling the same.
In order to implement the so-called three-path technique, i.e. an arbitrary selection of all knitting needles for knit, tuck and miss at a knitting system, numerous pattern devices are already known. These consist essentially of cam system parts forming knit, tuck and miss tracks and mechanical, electronic or electromagnetic control means, by means of which the knitting implements are distributed to these tracks.
In most knitting machines which are already known, which are designed for a three-path technique, either a substantial increase in the system width and/or a comparatively expensive construction of the pattern devices or the associated needles or jack has to be accepted. Thus for example a knitting machine is known (DE 3 739 924 A1) in which the control jacks associated with the knitting needles firstly have to be distributed at a first selector station in accordance with a pattern to a miss track and to a cam system track leading to the tuck position and then in a second selector station be left in accordance with the pattern in the tuck track or diverted into a knit track. Against the advantage that knitting needles and control jacks well-tried in practice can be used, there is the disadvantage that the double selection involves substantially doubling the system width, which means a large loss in performance on account of the small number of systems in any case possible, e.g. 48 systems with a needle cylinder diameter of 30". This disadvantage can indeed be avoided by a likewise known circular knitting machine (DE 4 007 253 C2), which makes the three-path technique possible without substantial system widening compared with the usual two-path technique. However such a knitting machine requires the use of special knitting needles with at least two pivotable control butts each instead of the generally used latch or slide needles, which is undesirable for reasons of cost.
Similar problems have arisen in the attempts to make other known selector devices previously used only for the two-path technique usable for the three-path technique. This applies for example to known selector devices (DE 3 712 673 C1) in which control jacks in the form of single arm levers are associated with the knitting needles and serve simultaneously as control elements and needle push-jacks. These control jacks are biased radially outwards by springs fitted in their backs, into a raise position and have to be swung on to the control magnet, which lies radially inside the needle circle, against the spring force before reaching the selection station, by means of a special presser race, which acts on rocking butts of the control jacks, in order thereby to lower the controllable raising butts into the needle tricks, i.e., swing them out into the working range of the cam system races. If such a selector device is used to make a double selection station, in that for example a second, corresponding selector device is arranged where the needles reach the tuck position, a second presser cam system part must be associated with this second selector device, in order to swing the control jacks running in the tuck position away from the corresponding raise part and apply them to a second control magnet. This second presser cam system part does indeed not double the system width as in the first cited knitting machines, but has the result that in no case can 60, 64 or 72 system be fitted round the periphery of a circular knitting machine with a needle cylinder diameter of 30", which is desirable for patterning reasons. In still further known knitting machines of this kind (DE-AS 1 760 405), which are also provided with control jacks in the form of single arm levers, each having a controllable raising butt, there is indeed the advantage that these already assume a position on reaching the tuck position which makes the use of a presser cam system part for the second control magnet unnecessary. A disadvantage with this solution is however the fact that the control jacks either each have to be provided on both sides with a spring or when using only one spring disposed on the front side of the control jacks, an additional tensioning cam system part is needed for this, which results in a corresponding unfavourable system widening as does a presser cam system part for the control jacks.
Finally a knitting machine has already been made known (DE 3 541 171 C2), which includes at least one knitting implement carrier, which comprises tricks and knitting implements slidably mounted therein, a cam system for guiding the knitting implements in pass or raise tracks, wherein the cam system and the carrier can be moved relative to one another, control jacks having controllable raising butts associated with the knitting implements for their selective transfer into the pass or raise track, which jacks are mounted slidably in the tricks of the carrier, are freely pivotable about bearing points which can abut the trick bottoms and have first and second lever arms to opposite sides of the bearing points, where the first lever arms are provided with armature surfaces and the second lever arms with rocking butts. Springs bearing on the trick bottoms are provided for biasing the second lever arms. At least one selector station with a control magnet adapted to cooperate with the armature surfaces and a presser cam system part serves for so swinging the control jacks that the armature surfaces are applied to the control magnet and are then selectively held or released thereby. The control magnet is located in this case on the front side of the control jacks. The pattern device developed as a whole for the particular case of a flat knitting machine is of comparatively complex construction. The control jacks serve only as control elements but not as needle push-jacks. Only a pre-selection is effected by them and the control magnet while the transfer of the needles into the tuck or knit position is effected with other means and at a location lying after the double selector station. The double selection is here effected in that all control jacks are applied to the control magnet at the first selector station by means of a presser cam, in order to select needles which are to be raised to a knitting position by pattern-based control of the control magnet, while the other needles are held deflected by an associated retaining pole against the forces of the springs, until they reach the second selector station, where a selection is made between the needles which are to be raised into a tuck position or which shall remain in a non-knitting position. The controllable raising butts in each case effect only a comparatively short lift of the control jacks, while the actual separation of the control jacks selected to knit, tuck and miss is effected in each case by means of an additionally present, second, non-controllable raising butt, which is formed on the lever arm of each control jack with the armature surface and always assumes a raise position regardless of the position of the controllable raising butt.
Such a selector device accordingly does not only involve a substantial increase in the system width and in the expense of construction but also does not operate with sufficient reliability, at least when used on circular knitting machines. Since the control jacks are held tight between the two selector stations solely by the holding magnet, it is not possible reliably to avoid the control jacks dropping uncontrollably off the hold magnet because of the action of the springs, therefore causing pattern faults, when vibration unavoidably occurs in rapidly running circular knitting machines.